Hot free forging is a method of producing a product by applying a pressure to an ingot heated to a high temperature to transform the ingot in various forms. Hot free forging may typically include a heating process, a forging process, a cutting process, and a heat treatment process.
In the case of inputting an ingot to a heating furnace to perform the heating process, a plurality of ingots may be simultaneously input to the heating furnace. The ingots simultaneously input to the heating furnace may be simultaneously output. In other words, the plurality of ingots input to the heating furnace cannot be removed from the heating furnace unless the entire heating process is completed.
An extended period of time may be consumed in performing the heating process, since an ingot having a large weight may be heated in the heating process. When the time for which the heating process is performed is extended, a greater amount of gas may be consumed, thereby increasing manufacturing costs. In addition, the amount of energy and the period of time consumed in the heating process may vary, depending on the composition of the plurality of ingots simultaneously input to the heating furnace.
Therefore, it is necessary to effectively categorize ingots to reduce the manufacturing costs of free forging.